A few months ago, when the White House was seeking to prevent independent counsel Kenneth W. Starr from questioning senior presidential advisers and lawyers, the legal argument came down to this: It's impossible to separate President Clinton's private life from his official duties.

Now, as the House prepares to vote tomorrow on launching formal impeachment proceedings against Clinton, the White House is taking the other side of the public-private debate. Stressing that the president's alleged lying under oath in the Paula Jones case concerned the purely private matter of his affair with Monica S. Lewinsky, the White House argument is that such actions are not crimes against the state and therefore do not rise to the level of impeachable offenses.

In the executive privilege dispute, it was Starr who said that discussions by senior aides about Clinton's dealings with Lewinsky were not legally protected because they involved matters relating to the president's personal life and not his official duties.

Then, the White House contended that it was impossible to draw such a bright line separating those two spheres. "Any conduct by the individual holding the Office of the President, whether it is characterized as private or official, can have substantial impact on a President's official duties," White House lawyers said in court papers.

The White House made a similar argument to defend its assertions of attorney-client privilege, saying that it was necessary for White House lawyers to be involved in discussions about the Jones case and Lewinsky because of the inevitable spillover of those private matters onto the president's ability to conduct his office.

The White House has so far lost its privilege fights, but a lower court judge agreed with its contention that executive privilege could cover discussions that ventured into the private realm.

As it mounts a last-ditch effort to head off an all but certain vote on the House floor to open an impeachment inquiry, the White House is now invoking the history of English impeachment proceedings, the intent of the framers and the findings of the Nixon impeachment inquiry nearly a quarter-century ago to argue that "high crimes and misdemeanors" refers exclusively to offenses "against the state."

Impeachment, the White House said in a memorandum to the House Judiciary Committee last week, should be "reserved for serious public wrongdoing of a serious political nature," not acts that are "essentially private."

University of Illinois law professor Ronald D. Rotunda, a consultant to Starr, said, "I don't understand how the same person can take both positions. . . . The president is simultaneously pleading executive privilege, which is a privilege of the state, while saying that the matters have nothing to do with the state and relate to his private affairs. That's inconsistent. And, secondly, we're talking not about what happened in a bedroom but what happened in the Oval Office."

Presidential special counsel Lanny A. Breuer said the White House was justified in both arguments. He said that White House lawyers needed to be able to discuss the Lewinsky matter with Clinton in confidence -- even though it concerned private conduct -- in large part because Starr's investigation was clearly leading to impeachment proceedings.

Now that that moment has arrived, Breuer added, the White House can -- without contradicting its former view -- argue that the president's private conduct does not rise to the level of an impeachable offense.

"It was clear from the process this was where we were going and I thought we needed to be involved in protecting and defending him, but I don't think the conduct is sufficient to impeach him," Breuer said. "So I don't think the two things are inconsistent. In fact, I think we were right."

University of Chicago law professor Cass Sunstein supported that. "It may be that the impeachment clause has a specific goal, that is to prevent people from being immune from removal when they've abused public authority, while at the same time saying that with respect to attorney-client or executive privilege it's very hard to make those kinds of distinctions . . . in view of the adverse effect on the office or the person," he said.